When my interlibrary loan arrived, I found a warning inscribed in pencil on one of the first pages of Mendeleyev's Dream: The Qeust for the Elements by Paul Strathern.
"This is a very shallow book," it said.
Horrors! My first thought on seeing this message was to wonder why anyone would do this to a book? I mean, write in it. Even in pencil. What a travasty! How insulting to the next reader! This penciler may have felt a civic duty to warn all subsequent readers about the depth of authorship; clearly, in this person's mind, none of us will be able to make a correct judgement on the quality of the work without prompting.
My second thought is that this penciler must be a very shallow reviewer. The book isn't shallow. No, it is a pleasant stroll through history with a docent who is very well informed and sometimes amusingly opinionated. This is a walk worth taking.
we should bear in mind that a pleasant stroll differs from wind sprints and from marathons. The book is not an extreme intellectual sport. It doesn't make a career or even clean the house; maybe it opens a few windows to the autumn air. The scope of the book is broad rather than deep, so I suppose that in a literal sense I should accept the judgement of shallowness, but I would argue differently. I would argue that a judgement of shallowness implies that a book does not reach to an appropriate depth for its purpose and audience. On the other hand, if the quantity of detail is chosen intelligently and matched to the purpose, then I think "shallow" is a poor description.
Indeed, a stroll through history encumbered by excessive argument and weight of detail would cease to be so pleasant a walk. More to the point, a book carrying such baggage would fail in its purpose of communicating a broad view of the development of modern chemistry; the broad view would be lost in the plethora of narrow observations and interpretations.
What I am proposing is this: Intellectual depth is best measured by reference to the objective of the work. When the objective is to establish the truth of some particular assertion, we can demand detailed observations and close reasoning. When the objective is to offer a different view over the existing body of knowledge, we ought to look for that kind of simplification which highlights the relationships which the author proposes to be most significant, coupled with coherence with established facts (which do not need to be reestablished in this work).
To review a book justly, whether in pencil or otherwise, requires that the reviewer correctly identify the objective and fairly assess whether the scope and presentation are effective in moving the reader toward that objective.